Liquid-crystalline medium

A liquid-crystalline medium comprising a mixture of polar compounds having positive dielectric anisotropy, wherein said mixture comprises one or more compounds of formula I,

• in which
• R is H, an alkyl or alkenyl radical having up to 15 carbon atoms which is unsubstituted, monosubstituted by CN or CF3 or at least monosubstituted by halogen, it also being possible for one or more CH2 groups in these radicals to be replaced, in each case independently of one another by, —O—,
• —CO—, —CO—O—, —CO—CO—, —S— or —O—CO—O— in such a way that O atoms are not linked directly to one another,
• A1
• (a) is a trans-1,4-cyclohexylene radical in which, in addition, one or more non-adjacent CH2 groups may be replaced, in each case independently, by —O— or —S—, or a 1,4-cyclohexenylene radical,
• (b) is a 1,4-phenylene radical, in which, in addition, one or two CH groups may be replaced by N,
• (c) is a radical from the group consisting of 1,4-bicyclo[2.2.2]octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl and 1,2,3,4-tetrahydronaphthalene-2,6-diyl,
• wherein the radicals (a) and (b) may be monosubstituted or polysubstituted by CN, CH3 or F,
• Z1 is —CO—O—, —O—CO—, —CH2—O—, —OCH2—, —CH2CH2—, —CF2O—, —OCF2—, —CH═CH—, —C≡C—, —(CH2)4—, —CH═CH—CH2CH2— or a single bond,
• Y is F, Cl, halogenated alkyl having 1 to 6 carbon atoms, halogenated alkenyl having up to 6 carbon atoms, or halogenated alkoxy having 1 to 6 carbon atoms,
• L is H or F, and
• m is 0 or 1;
• and
• said mixture also comprises one or more compounds of the formula
• wherein
• R0 is n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having up to 9 carbon atoms;
• and
• X0 is F, Cl, halogenated alkyl having 1 to 6 carbon atoms, halogenated alkenyl having up to 6 carbon atoms, or halogenated alkoxy having up to 6 carbon atoms, and
• wherein said mixture additionally comprises one or more compounds of formula XI
• in which
• R0 is n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having up to 9 carbon atoms,
• X0 is F, Cl, halogenated alkyl having 1 to 6 carbon atoms, halogenated alkenyl having up to 6 carbon atoms, or halogenated alkoxy having up to 6 carbon atoms, and
• Y1 and Y2 are in each case, independently of one another, H or F, and
• said medium has a clearing point of higher than 100° C.

A liquid-crystalline medium comprising a mixture of polar compounds having positive dielectric anisotropy, wherein said mixture comprises one or more compounds of formula I,

• in which
• R is H, an alkyl or alkenyl radical having up to 15 carbon atoms which is unsubstituted, monosubstituted by CN or CF3 or at least monosubstituted by halogen, it also being possible for one or more CH2 groups in these radicals to be replaced, in each case independently of one another, by —O—,
• —CO—, —CO—O—, —O—CO—, —S— or —O—CO—O— in such a way that O atoms are not linked directly to one another,
• A1
• (a) is a trans-1,4-cyclohexylene radical in which, in addition, one or more non-adjacent CH2 groups may be replaced, in each case independently, by —O— or —S—, or a 1,4-cyclohexenylene radical,
• (b) is a 1,4-phenylene radical in which, in addition, one or two CH groups may be replaced by N,
• (c) is a radical from the group consisting of 1,4-bicyclo[2.2.2]octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl and 1,2,3,4-tetrahydronaphthalene-2,6-diyl,
• wherein the radicals (a) and (b) may be monosubstituted or polysubstituted by CN, CH3 or F,
• Z1 is —CO—O—, —O—CO—, —CH2—O—, —OCH2—, —CH2CH2—, —CF2O—, —OCF2—, —CH═CH—, —C≡C—, —(CH2)4—, —CH═CH—CH2CH2— or a single bond,
• Y is F, Cl, halogenated alkyl having 1 to 6 carbon atoms, halogenated alkenyl having up to 6 carbon atoms, or halogenated alkoxy having 1 to 6 carbon atoms,
• L is H or F, and
• m is 0 or 1;
• and
• said mixture also comprises one or more compounds of the formula
• wherein
• R0 is n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having up to 9 carbon atoms;
• and
• X0 is F, Cl, halogenated alkyl having 1 to 6 carbon atoms, halogenated alkenyl having up to 6 carbon atoms, or halogenated alkoxy having up to 6 carbon atoms,
• wherein said mixture additionally comprises one more compounds of formula XI
• in which
• R0 is n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having up to 9 carbon atoms,
• X0 is F, Cl, halogenated alkyl having 1 to 6 carbon atoms, halogenated alkenyl having up to 6 carbon atoms, or halogenated alkoxy having up to 6 carbon atoms, and
• Y1 and Y2 are in each case, independently of one another, H or F, and
• wherein the amount of compounds of formula XI is at least 5 wt %.

A liquid-crystalline medium comprising a mixture of polar compounds having positive dielectric anisotropy, wherein said mixture comprises one or more compounds of formula I,

• in which
• R is H, an alkyl or alkenyl having up to 15 carbon atoms which is unsubstituted, monosubstituted by CN or CF3 or at least monosubstituted by halogen, and in which one or more CH2 groups are each replaced by —O— in such a way that O atoms are not linked directly to one another,
• A1
• (a) is a trans-1,4-cyclohexylene radical in which, in addition, one or more non-adjacent CH2 groups may be replaced, in each case independently, by —O— or —S—, or a 1,4-cyclohexenylene radical,
• (b) is a 1,4-phenylene radical, in which, in addition, one or two CH groups may be replaced by N,
• (c) is a radical from the group consisting of 1,4-bicyclo[2.2.2]octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydro-naphthalene-2,6-diyl and 1,2,3,4-tetrahydro-naphthalene-2,6-diyl,
• wherein the radicals (a) and (b) may be monosubstituted or polysubstituted by CN, CH3 or F,
• Z1 is —CO—O—, —O—CO—, —CH2—O—, —OCH2—, —CH2CH2—, —CF2O—, —OCF2—, —CH═CH—, —C≡C—, —(CH2)4—, —CH═CH—CH2CH2— or a single bond,
• Y is F, Cl, halogenated alkyl having 1 to 6 carbon atoms, halogenated alkenyl having up to 6 carbon atoms or halogenated alkoxy having 1 to 6 carbon atoms,
• L1 is H or F, and
• m is 0 or 1;
• said mixture also comprises one or more compounds of the formula
• wherein
• R0 is n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having up to 9 carbon atoms, and
• X0 is F, Cl, halogenated alkyl having 1 to 6 carbon atoms, halogenated alkenyl having up to 6 carbon atoms, or halogenated alkoxy having 1 to 6 carbon atoms, and
• wherein said mixture additionally comprises one or more compounds of formula XI
• in which
• R0 is n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having up to 9 carbon atoms,
• X0 is F, Cl, halogenated alkyl, alkenyl or alkoxy having 1 to 6 carbon atoms, and
• Y1 and Y2 are in each case, independently of one another, H or F.